The present invention relates to a rotary press for manufacturing tablets and the like.
In known presses for manufacturing tablets and the like, granular material is deposited from a feeder onto the upper surface of a die table for delivery of the material into die cavities carried by the die table. Upper and lower punches are positioned in aligned openings of upper and lower turret parts that are spaced on opposite sides of the die table. The turret portions and the die table are secured to a drive shaft for synchronous rotation of the turret portions and die table by the press. Track guides or cam structure supported by the press provide for reciprocation of the upper and lover punches to compress the material that has been deposited in the die cavities of the die table.
The upper and lower punches of prior art presses reciprocate in sliding contact directly with openings formed in the turret. This construction limits the punches that may be used in the press to those having relevant outer dimensions approximating the opening to provide for sliding contact between the punches and the turret portions. Furthermore, the repetitive reciprocation required by the sliding punches results in wear or other damage to the punches and to the surfaces of the turret parts that come into contact with the punches. Because the sliding contact surfaces receiving the punches are integral to the turret parts, damage to the sliding contact surfaces represents damage to the entire turret part.
The present invention provides removable punch assemblies for a rotary press in which the sliding surfaces for the punches are contained within the punch assembly. The inclusion of the sliding surfaces within removable punch assemblies provides for variation in the dimensions of applicable punches thereby leading to a more universal press. Also, the inclusion of the sliding contact surfaces within the removable punch assemblies allows different material to be used for the contact surface of the punch assembly as compared to the material selected for the turret portion. This provides for increased control over the portions of the punches and support structure which come into contact and are subject to wear or damage. Furthermore, when the sliding surfaces provided for one of the punches become worn or otherwise damaged, the inclusion of the sliding surfaces within removable punch assemblies allows for replacement of an individual punch assembly rather than replacement of an entire turret portion.
Additionally, conventional presses incorporate a separate die table located between the punch-carrying turret portions. The die tables carry the die cavities in which the material to be compressed is delivered by a feeder. This construction requires that the die table be secured to the drive shaft of the press or to one or both of the turret portions such that the die cavities and punches rotate synchronously.
The removable punch assemblies of the present invention eliminate the need for a separate die table. The punch assemblies include a die portion having a material chamber in which the material to be compressed is delivered. This construction provides for a more versatile and efficient assembly as compared with conventional tableting presses.
According to the present invention there is provided a rotary tableting press. The tableting press includes a turret rotatably supported by a housing and having upper and lower carousels. The upper and lower carousels have aligned openings in which upper and lower punch assemblies are removably supported. Each of the punch assemblies includes a punch casing and a punch member slidably received in an opening of the punch casing. The rotary tablet press further includes means to reciprocate the punches within the punch casings.
According to an embodiment of The invention the reciprocating means includes means for biasing the upper and lower punch members, the means for biasing upwardly biasing the upper punch members and downwardly biasing the lower punch members. Rollers supported by the housing engage the punches to direct the upper and lower punches toward each other to form a tablet through compression of material located between the punches.
According to an embodiment of the present invention, the central opening in each of the lower casings consists of a central bore having a terminal end and each of the casings includes a removable die portion extending from the terminal end of the bore to an end of the casing. The die portion includes an opening defining a material chamber extending through the die portion.
According to another embodiment of the present invention, each of the upper and lower punch members includes mold recesses. The mold recesses are positioned such that the upper and lower mold recesses are brought into an intimate confronting relationship as, the punch members engage the cam structure to form a tablet through compression of material which has been placed between the mold recesses.
The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments discussed below and as illustrated in the accompanying figures. As will be realized, the invention is capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive.